[Federal Register Volume 60, Number 53 (Monday, March 20, 1995)]
[Rules and Regulations]
[Pages 14619-14621]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-6684]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-SW-22-AD; Amendment 39-9177; AD 95-06-07]
Airworthiness Directives; Robinson Helicopter Company Model R22
Helicopters
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD), applicable to Robinson Helicopter Company (RHC) Model R22
helicopters, that currently requires an initial dye penetrant
inspection of the main rotor drive forward flexplate (flexplate), and
repetitive visual inspections of certain installed flexplates. This
amendment is prompted by three accidents reported by the airworthiness
authority of Australia involving failure of the flexplate, located
between the main rotor gearbox and clutch assembly. The actions
specified by this AD are intended to prevent failure of the flexplate,
failure of the main rotor drive system, and subsequent loss of control
of the helicopter.
DATES: Effective April 4, 1995.
Comments for inclusion in the Rules Docket must be received on or
before May 19, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Office of the Assistant Chief Counsel, Attention:
Rules Docket No. 94-SW-22-AD, 2601 Meacham Boulevard, Room 663, Fort
Worth, Texas 76137-4298.
FOR FURTHER INFORMATION CONTACT: Ms. Elizabeth Bumann, Aerospace
Engineer, Los Angeles Aircraft Certification Office, Propulsion Branch,
FAA, 3960 Paramount Blvd., Lakewood, California 90712, telephone (310)
627-5265, fax (310) 627-5210.
SUPPLEMENTARY INFORMATION: On May 18, 1994, the FAA issued Priority
Letter AD 94-11-01, applicable to RHC Model R22 helicopters, to require
an initial dye penetrant inspection of the flexplate on all RHC Model
R22 helicopters, and repetitive visual inspections of flexplates that
have been in service for 2 or more years or 500 or more hours time-in-
service (TIS). That action was prompted by three accidents reported by
the airworthiness authority of Australia involving failure of the
flexplate. In one accident, the flexplate fractured during
[[Page 14620]] normal cruise flight releasing several fragments, some
of which punctured the fuel tank. A metallurgical report issued by the
airworthiness authority of Australia suggests that the failures
resulted from fatigue cracking that initiated at areas of intergranular
pitting corrosion on the edge of the flexplates. The FAA has determined
that any crack, nick, or corrosion in the flexplate creates an unsafe
condition and should be corrected. That condition, if not corrected,
could result in failure of the flexplate, failure of the main rotor
drive system, and subsequent loss of control of the helicopter.
Since the issuance of that AD, the FAA has received information
indicating that flexplates, part number (P/N) A193-1 without bonded
washers, and P/N A947-1 with bonded washers, may have been subjected to
paint overspray at Robinson Helicopter Company when they were painting
hardware adjacent to the flexplate. Damage to flexplate edges with
paint overspray could result in corrosion due to the retention of
contaminants under the paint. Robinson Helicopter Company has revised
their inspection procedures to ensure that subsequently-produced
flexplates are not subject to the paint overspray. This corrective
procedure was implemented with the production of flexplate, P/N A947-
1E. In addition, flexplate, P/N A947-1E is stronger and more resistant
to corrosion damage than the previously-designed flexplates. Therefore,
the initial dye penetrant inspection for cracks and repetitive visual
inspections for nicks, cracks, or corrosion may be terminated upon
installation of this improved flexplate or a subsequent FAA-approved
revision to P/N A947-1E.
The reference to the flexplate's TIS in paragraph (b) of the
Priority Letter AD has been clarified to require that the repetitive
visual inspections in paragraph (d) of the AD be conducted upon
reaching 2 years or 500 hours TIS on the flexplate. If the flexplate
TIS cannot be determined through a review of the log book, the
helicopter TIS must be used to determine the TIS of the flexplate.
Paragraph (c) has been revised to delete the reference to the
repetitive visual inspections for flexplates used to replace those that
were determined to have cracks as a result of the inspection of
paragraph (a) of the Priority Letter AD. This deletion changes the
lettering of the subsequent paragraphs. The FAA has determined that
these changes will neither increase the economic burden on any operator
nor increase the scope of the AD.
Since an unsafe condition has been identified that is likely to
exist or develop on other Robinson Helicopter Company Model R-22
helicopters of the same type design, this AD supersedes Priority Letter
AD 94-11-01, to require a one-time dye penetrant inspection of the
flexplate, P/N A193-1 without bonded washers and P/N A947-1 with bonded
washers, for cracks within the next 25 hours TIS, and replacement if a
crack is found. Additionally, for flexplates that have been in service
for 2 or more years or 450 or more hours TIS, repetitive visual
inspections of the flexplate for nicks, cracks, or corrosion are
required at intervals not to exceed 50 hours TIS. This AD also provides
for repair of the flexplate if a nick or corrosion is found, or
replacement if a crack is found. The flexplate connects the gearbox and
the clutch shaft, and failure of the flexplate could lead to failure of
the driveshaft and loss of power to the rotor system. Due to the
critical need for the flexplate to ensure the continued safe flight of
the affected helicopters, this rule must be issued immediately to
correct an unsafe condition in aircraft.
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this rule by
submitting such written data, views, or arguments as they may desire.
Communications should identify the Rules Docket number and be submitted
in triplicate to the address specified under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the rule. All comments submitted will be
available, both before and after the closing date for comments, in the
Rules Docket for examination by interested persons. A report that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 94-SW-22-AD.'' The postcard will be date stamped and
returned to the commenter.
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, may be obtained from the Rules Docket at the
location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
[[Page 14621]]
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness
directive (AD), Amendment 39-9177, to read as follows:
AD 95-06-07 Robinson Helicopter Company: Amendment 39-9177. Docket
Number 94-SW-22-AD. Supersedes Priority Letter AD 94-11-01, issued
May 18, 1994.
Applicability: Model R22 helicopters, with forward flexplate
(flexplate), part number (P/N) A947-1 with bonded washers, or P/N
A193-1 without bonded washers, installed, certificated in any
category. Flexplate, P/N A947-1E and subsequent FAA-approved
revisions to P/N A947-1, is exempt from the requirements of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the flexplate, failure of the main rotor
drive, and subsequent loss of control of the helicopter, accomplish
the following:
(a) Within the next 25 hours time-in-service (TIS) after the
effective date of this airworthiness directive (AD), accomplish the
following:
(1) With the clutch disengaged, support the forward end of the
clutch shaft, P/N A166-1, remove the flexplate, and record the shim
locations for use during reinstallation.
(i) Replace any flexplate that does not have eight bonded
washers (two per arm) with an airworthy flexplate, P/N A947-1E or a
subsequent FAA-approved revision to P/N A947-1.
(ii) For those flexplates that have eight bonded washers (two
per arm), comply with the following:
(2) Remove all coating down to bare metal from the outer edges
of the flexplate to approximately 0.125 inches inward, but in no
case within 0.50 inches of the bonded washers, using Scotch Brite or
600 grit sand paper. Do not use a chemical paint stripper since it
may adversely affect the adhesive that bonds the washers to the
flexplate.
(3) Inspect the outer edges of the flexplate for cracks,
avoiding the bonded washers, using a dye penetrant inspection method
in accordance with Appendix I of this AD. If the dye penetrant
contacts the bonded washers, remove the solution from the bonded
washers within 1 minute since longer exposure may adversely affect
the adhesive.
(i) If a crack is found, replace the flexplate with an airworthy
flexplate, P/N A947-1E or a subsequent FAA-approved revision to P/N
A947-1.
(ii) If no crack is found, paint the bare edge area of the
flexplate with an even coat of zinc-chromate or epoxy primer. Do not
paint the bare metal surface of the bonded washers.
(4) Reinstall the flexplate and ensure sheave and clutch shaft
angle are properly aligned in accordance with the applicable
maintenance manual.
(b) For those helicopters with flexplates that have less than 2
years or 450 hours TIS, accomplish the following prior to or upon
reaching 2 years or 500 hours TIS, and thereafter at intervals not
to exceed 50 hours TIS from the last inspection; for those
helicopters with flexplates that have 2 years or more or 450 hours
or more TIS, accomplish the following at intervals not to exceed 50
hours TIS from the last inspection. (If the flexplate TIS cannot be
determined through a review of the maintenance records, then use the
helicopter TIS as the TIS of the flexplate).
(1) Remove the flexplate in accordance with the applicable
maintenance manual.
(2) Clean the flexplate using a solvent (e.g., methyl-ethyl
ketone or naphtha).
(3) Inspect the flexplate for nicks, cracks, or corrosion using
a 10-power or higher magnifying glass, paying close attention to the
edges of the flexplate.
(i) If a crack is found, replace the flexplate with an airworthy
flexplate, P/N A947-1E or a subsequent FAA-approved revision to P/N
A947-1, in accordance with the applicable maintenance manual.
(ii) If a nick or corrosion is found, repair the flexplate in
accordance with the applicable maintenance manual.
(iii) Paint any bare edges of the flexplate with an even coat of
zinc-chromate or epoxy primer. Do not paint the bare metal surface
of the bonded washers.
(iv) If any nick or corrosion cannot be repaired within the
rework limits specified in the applicable maintenance manual,
replace the flexplate with an airworthy flexplate, P/N A947-1E or a
subsequent FAA-approved revision to P/N A947-1, in accordance with
the applicable maintenance manual.
(4) Reinstall the flexplate and ensure sheave and clutch shaft
are properly aligned in accordance with the applicable maintenance
manual.
Note 1: Robinson Helicopter Company R22 Maintenance Manual,
Change 14, dated March 14, 1994, pertains to this AD.
(c) If a crack, nick, or corrosion is found on the flexplate as
a result of the inspections required by this AD, report a
description of the crack, nick, or corrosion, the total TIS, and the
operating conditions to the Manager, Propulsion Branch, Los Angeles
Aircraft Certification Office, FAA. Reporting requirements have been
approved by the Office of Management and Budget and assigned control
number 2120-0056.
(d) Installation of a flexplate, P/N A947-1E or a subsequent
FAA-approved revision to P/N A947-1, constitutes terminating action
for the requirements of this AD.
(e) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used when approved by the Manager, Los Angeles Aircraft
Certification Office, FAA. Operators shall submit their requests
through an FAA Principal Maintenance Inspector, who may concur or
comment and then send it to the Manager, Los Angeles Aircraft
Certification Office.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles Aircraft Certification Office.
(f) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the helicopter to a location where
the requirements of this AD can be accomplished.
(g) This amendment becomes effective on April 4, 1995.
Appendix I--Dye Penetrants
Several dye penetrant type inspection kits are now available
that will reveal the presence of surface cracks or defects and
subsurface flaws that extend to the surface of the part being
inspected. These penetrant type inspection methods are considered
acceptable, provided the part being inspected has been thoroughly
cleaned, all areas are readily accessible for viewing, and the
manufacturer's recommendations as to the method of application are
closely followed.
a. Cleaning. An inspection is initiated by first cleaning the
surface to be inspected of dirt, loose scale, oil, and grease.
Precleaning may usually be accomplished by vapor degreasing or with
volatile cleaners. Use a volatile cleaner as it will evaporate from
the defects before applying the penetrant dye. Sand blasting is not
as desirable a cleaning method, since surface indications may be
obscured. It is not necessary to remove anodic films from parts to
be inspected, since the dye readily penetrates such films. Special
procedures for removing the excess dye should be followed.
b. Application of Penetrant. The penetrant is applied by
brushing, spraying, or by dipping and allowing to stand for a
minimum of 2 minutes. Dwell time may be extended up to 15 minutes,
depending upon the temperature of the part and fineness of the
defect or surface condition. Parts being inspected should be dry and
heated to at least 70 deg. F, but not over 130 deg. F. Very small
indications require increased penetration periods.
c. Removal of Dye Penetrant. Surplus penetrant is usually
removed by application of a special cleaner or remover, or by
washing with plain water and allowing the part to dry. Water rinse
may also be used in conjunction with the remover, subject to the
manufacturer's recommendations.
d. Application of Developer. A light and even coat of developer
is applied by spraying, brushing, or dipping. When dipping, avoid
excess accumulation. Penetrant that has penetrated into cracks or
other openings in the surface of the material will be drawn out by
the developer resulting in a bright red indication. Some idea of the
size of the defect may be obtained after experience by watching the
size and rate of growth of the indication.
Issued in Fort Worth, Texas, on March 10, 1995.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 95-6684 Filed 3-17-95; 8:45 am]
BILLING CODE 4910-13-P
